Feasibility of Endoscopic Treatment of Middle Ear Myoclonus: A Cadaveric Study

Stapedius and tensor tympani tenotomy is a relatively simple surgical procedure commonly performed to control pulsatile tinnitus due to middle ear myoclonus and for several other indications. We designed a cadaveric study to assess the feasibility of an entirely endoscopic approach to stapedius and tensor tympani tenotomy. We performed this endoscopic ear surgery in 10 cadaveric temporal bones and summarized our experience. Endoscopic stapedius and tensor tympani section is a new, minimally invasive treatment option for middle ear myoclonus that should be considered as the first line surgical approach in patients who fail medical therapy. The use of an endoscopic approach allows for easier access and vastly superior visualization of the relevant anatomy, which in turn allows the surgeon to minimize tissue dissection. The entire operation, including raising the tympanomeatal flap and tendon section, can be safely completed under visualization with a rigid endoscope. 1. Introduction Middle ear myoclonus is an infrequent but well-known cause of pulsatile tinnitus. It was first described by Adam Politzer in the late 19th century and is still not a clearly understood clinical entity. Occasionally, a causative lesion can be identified on magnetic resonance imaging (MRI) in the Guillain-Mollaret triangle in the brainstem and cerebellum, also known as the myoclonic triangle; however, most cases are idiopathic. The quality of pulsatile tinnitus associated with middle ear myoclonus is variable and described by patients most frequently as crackling, but also clicking, tapping, thumping, pulsations, fluttering moth, machinery rumble, and whooshing sounds. When myoclonus is slower, individual clicks can be discerned, once the pace of muscle contraction is faster, the sound blends into one continuous tone. Sometimes middle ear myoclonus is described as a sound slowly escalating over several minutes, only to stop abruptly. This cycle may repeat and these slowly waxing and abruptly stopping episodes may occur frequently throughout the day. The etiology of this condition is attributed to the myoclonic contraction of one of the two middle ear muscles, namely the stapedius and/or tensor tympani muscles [1–3]. Given the relative rarity of the condition, the majority of published literature on this condition takes the form of case reports or small case series. In 2013, Park et al. [4] reported the largest known series with 58 patients treated for middle ear myoclonus. Conservative and medical therapy is thought to be first line of treatment utilizing muscle relaxants,